I currently get a new report every month in xls format which I have to spend
a few hours to manualy find duplicates from the last report before i can
process any new tasks required. I have tried a few tips and formulars found
online but they dont give great results.

In Short what I would like to do is open the new report compare it to the
older one which contains more information and delete any duplicate data
enteries in where coloum a is the control. Or task id. If I could do this I
would then be left with only new tasks to process and not have to waste a few
hours making sure I am not duplicating work.

Many thanks in advance.